Reuse or create new Form?

In my code, whenever a node in a Tree is selected, another pane shows a corresponding Form.
Currently my code always creates a new Form passing it a FieldGroup as data.

FieldGroup fg = new FieldGroup();
fg.setItemDataSource(item); // item selected in Tree
Component c;
c = new MyForm(fg);
} else {
c = new MyOtherForm(fg);

Is it better to reuse the Form? Will this make a difference in how fast the form is shown on the client?
Should I then also reuse the FieldGroup and just set another dataSource? Or use a new FieldGroup and rebind all fields in the Form?

Thanks for your recommendations